Infra-red burner

ABSTRACT

There is disclosed an infra-red burner particularly suitable for process lines in which higher temperatures of the burner are possible to be attained by a material which while intended as an insulating material in its ordinary and everyday common use, in fact provides improved thermal stability when used as a burner face member, density being such that it is permeable to a gas/air mixture and yet the flame is retained exceptionally close to the surface, without flashback, a particularly important aspect of the construction resulting in the ability to modulate heat production and in fact make possible initiation and termination of such production nearly instantaneously.

United States; Patent [451 Jan.15,1974

Bratko lNFRA-RED BURNER [76] Inventor: Rudolph S. Bratko, 10706 Harvard Ave., Cleveland, Ohio 44109 [22] Filed: Mar. 31, 1972 [21] Appl. No.: 239,951

[52] US. Cl. 431/328 [51] Int. Cl. F23d 13/12 [58] Field of Search; 431/328, 329

[56] References Cited UNITED STATES PATENTS 3,188,366 6/1965 Flynn 431/329 3,449,137 6/1969 Ekdah1.... 106/50 3,422,811 1/1969 Strand 431/329 3,248,099 4/1966 Bratko 263/6 R Primary ExaminerCarro1l B. Dority, Jr. Att0rneyRobb & Robb 5 7 ABSTRACT There is disclosed an infra-red burner particularly suitable for process lines in which higher temperatures of the burner are possible to be attained by a material which while intended as an insulating material in its ordinary and everyday common use, in fact provides improved thermal stability when used as a burner face member, density being such that it is permeable to a gas/air mixture and yet the flame is retained exceptionally close to the surface, without flashback, a particularly important aspect of the construction resulting in the ability to modulate heat production and in fact make possible initiation and termination of such production nearly instantaneously.

6 Claims, 6 Drawing Figures PATENTEDJAH I 51974 n l L 11:.

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FIG. 3

I lNFRA-RED BURNER OBJECTS OF THE INVENTION It is a primaryobject of this invention to provide an improvement over my prior invention disclosed in my prior U.S. PaLNo. 3,248,099 dated Apr.'26, 1966, wherein failure of the burner face is eliminated hereby.

In my prior patent, I availed of a material in which the temperatures desired to be provided for most efficient production of infra-red radiation were so high that the material did not have sufficient thermal stability to permit continuous operation. By way of example, the prior material was really only thermally stable up to 2,300 F., whereas the flame temperature sought to be maintained was 2,400 F., resulting in deterioration of the material comprising the burner face.

In contrast, the instant invention avails of a material in which the thermal stability at flame temperatures of 2,400" F., is in the range of 95 percent and even at 2,700 F., minimum stabilty is not less than 40 percent.

Further, the new material has substantially greater physical resistance to sagging and deforming, making possible the use of unsupported areas substantially greater than heretofore known.

It is a further object of the invention to provide a burner of such construction that it may be used in elongated form, having substantially unobstructed face areas wherein the infra-red radiation is produced over a wide area and of such configuration as will provide for the use of multiple burners.

Another object of the invention is to provide a burner of the class described, in which distribution of the flame over the face of the burner is uniform, and at maximum temperature, still does not penetrate the said face to any great extent, retaining the flame development very close to such surface .in part owing to theinsulating qualities of the material.

Yet a further object of the invention is to provide a burner of such construction as will facilitate the.replacement of the burner face should such be necessary, owing to usual circumstances or to physical damage which the burner face cannot resist, although normally it is constructed to resist usual physical impact.

One of the important objects of the invention is to provide a burner in which temperaturemodulation is possible with considerable accuracy and in fact virtually instantaneous changes in heat production may be effected.

Other and further objects of the invention will be understood from a consideration of the specification appended hereto and disclosed in the drawing, wherein:

FIG. 1 is a somewhat diagrammatic view in side elevation of a process line involving a conveyor and suggesting the positioning of burners of the herein described construction thereabove with certain instrumentalities usually provided for such burners.

FIG. 2 is a bottom view of a burner constructed in accordance with this invention.

FIG. 3 is a view in end elevation of the burner in this case turned upside down, with the face upward.

FIG. 4 is a fragmentary sectional view taken through the burner and plenum.

FIG. 5 is a plan view of the diffuser used in the burner.

FIG. 6 is an end view of the diffuser shown in FIG. 5.

DESCRIPTION OF THE INVENTION Referring now to FIG. I preliminarily, there is disclosed a process line which may be generally described as an oven 1, in which an endless belt conveyor 2 is mounted so as to provide for an upper lap of conveyor at 3 and a lower lap 4 which is positioned by the small rolls 5 at each end, the'upper lap 3 passing over the large rollers 6 at corresponding ends.

It will be understood that this is intended to be diagrammatic, and not to illustrate in detail any particular.

form of conveyor but to show a potential process line.

In this instance, there is disclosed one of the burners generally designated 7 above one portion of the upper lap 3 of the conveyor 2 with alike'burner 7 adjacent thereto but of the opposite hand mounted parallel therewith and in line with the conveyor lap 3 likewise.

The burner units 7 are supplied by suitable gas and air mixture lines 8 and 9, these leading to a common line 10 which is supplied from a blower mixer unit generally designated 1 l, in which air is supplied from a line 12 and gas through a line 13 leading to the blower unit lll.

In this instance the blower operates with an approximate 2% ounce premix of gas/air on a ratio of 10 parts of air to one part of gas.

Turning now to a consideration of the other figures in the drawing, FIG. 2 showing as it does a bottom view of one of the burners 7, is referred to at this point, in conjunction with FIG. 4 to describe the plenum M which is a rectilinear member having the upright sides 15 extending longitudinally, the ends 16 transversely therebetween and the bottom 17 to which the sides and ends are connected, forming an open shallow pan-like member which in the manner being described is open upwardly, it being understood that the burner is in this description upside down in effect.

Extending around the upper edges of the sides and ends, is an angle shelf or support suggested at 20 in FIG. 4, which is fixed in any suitable manner to the side and end walls 15 and 16 as by welding,'riveting or otherwise.

This angle arrangement is availed of to support the burner face member generally designated 21 which, in this instance, is formed of a special insulating material, designed initially for use as insulation, and as faras is known only used for insulation by others, there being no comparable use in a burner of this kind apparently availed of.

As will be understood, this burner face member 2ll is itself a rectilinear unit, in reality a sort of board which is for the sake of understandable description approximately seven-eighths inch thick in its normal use and of whatever width, in this instance approximately 1 foot, and perhaps as much as 6 feet long, mounted or supported on the angle member 20 previously referred to.

In order to retain this burner face member in position, holding instrumentalities are provided in the form of additional angle parts 22 which are equipped with nut sections 23 at their lower ends, the nut sections being engaged by bolts such as 24 extending upwardly through a mounting member 25, there being a series of these nut portions, bolts and mounting members as will be appreciated and as suggested in FIG. 2 extending around the periphery of the plenum.

It must be understood that by suitable manipulation of the bolt 24 as by turning the head 26 thereof, in each case, the angle 22 may be drawn downwardly to compress the edges of the board 21 between the angle 22 and the angle 20 and thereby maintain the board 21 in position.

Suitable means such as aluminum foil or the like 27, may be used between the angle 22 and board 21 to enable the removal of the board'21 when necessary.

Mounted within the body 14, is a diffuser generally designated 30 which is made of foraminated material having a series of openings 31 therein and extending over the face of said diffuser, and of suitable size, in this instance about one-fourth inch diameter on fivesixteenths inch centers.

The diffuser is bent into a V-shaped arrangement along the line 32 and thus may assume the position suggested in FIG. 3 in inverted arrangement and being mounted so as to be supported on the bottom 17 and fixed thereto in accordance with desired practice.

Suitably engaged about midway of the bottom of the burner is a pipe connection 33 which leads into the interior and beneath the diffuser, being connected to the pipe such as 8 or 9 as the case may be whereby gas and air mixture may be introduced to the interior and beneath the diffuser 30.

The burner may be lighted in the usual manner, and since the material of the burner face is an alumina silica composition which is in this instance one having a chemical analysis of silicon oxide about 55 percent, aluminum oxide about 40.5 percent, chromic oxide about 4 percent with about 0.2 percent ferric oxide and 0.15 percent sodium oxide.

It should be explained in this connection that the composition of this material is quite a bit different from my prior patent disclosure, and whereas in the prior patent disclosure the thermal stability of the material was substantially less than is provided by the material hereinbefore just described, in fact since the temperature of the flame at the surface of the burner in this instance is in the neighborhood of 2,400 F., and the thermal stability of the prior material markedly deteriorated at that point, the instant material is a vast improvement since it provides thermal stability substantially greater and up to 2,700 F., in any event.

In accordance with the known analysis of this material, the thermal stability is not less than 40 percent at 2,700 E, and remains at substantially 95 percent at 2,400 F., which is the usual operating temperature of the burner hereinbefore described.

It will thus be seen that a vast improvement has been provided by the invention hereinbefore described, availing of the improved material in which the chromic oxide is apparently an important factor.

In any event, the material is further described as being a fibrous felt of a refractory nature, retaining its fibrous form in contrast to sintering and marked embrittlement of other materials used under the same conditions. This insulating material is a product of Johns- Manville and often referred to under the trademark Fibrechrome having been developed by that company for insulating purposes.

The composition of the burner face member 21, de-

scribed in detail herein, makes possible some most favorable adjustments particularly when the burner is used in certain types of process lines which may be set up for processing certain materials.

For example, if it be assumed that a heat sensitive material as a textile or the like is moving along under the burner 7 of FIG. 1, and for some reason a sudden stoppage of the same occurs for whatever reason, the heat may be likewise turned off to prevent damage to the material.

In view of the fact that controls may be provided which will shut down the burners, and that the residual heat therein is extremely low, no damage to the material beneath such bumers will be caused. In actual use, the burner face temperature will drop to a point at which a persons hand may be touched thereto within three to four seconds after shut-off from a temperature of 900 to 1,000 F., or even higher.

On the other hand, after start-up or ignition of the fuel/air mixture, temperature will rise to an initial setting in the range described within an equally short time.

Control of temperature may be accomplished by varying fuel/air mix or in other ways suggested by the foregoing.

I claim:

1. An infra-red burner unit of the class described, comprising a plenum of open sided configuration, said open side being arranged to receive a burner face member thereover to cover the same, said member consisting of a fibrous felt thermal insulation material of alumina-silica composition, having a substantial chromic oxide content, and of a density to be selfsupporting, a diffuser in the plenum, and means to supply a gas/air mixture under pressure to force the same though the burner face member.

2. A burner unit as claimed in claim 1, wherein the plenum is an elongated rectilinear body, the diffuser is V-shape in end elevation, and extends longitudinally of the body with the apex directed toward the burner face member, and the thickness of the burner face member is approximately one-fifth the total depth of the plenum.

3. A burner unit as claimed in claim 2, wherein the face member includes approximately 4 percent chromic oxide.

4. A burner unit as claimed in claim I, wherein the face member includes approximately 55 percent silicon dioxide, 40 percent aluminum oxide and 4 percent chromic oxide with traces of sodium oxide and ferric oxide.

5. A burner unit as claimed in claim 1, wherein the insulation material has a density of not more than 12 pounds per cubic foot, and a thermal stability of not less than 40 percent at 2,700 F.

6. A burner unit as claimed in claim 4, wherein the material comprising the face member has a density of not more than 12 pounds per cubic foot, and can be fired for operation at an ambient temperature of approximately 2,000 F. 

1. An infra-red burner unit of the class described, comprising a plenum of open sided configuration, said open side being arranged to receive a burner face member thereover to cover the same, said member consisting of a fibrous felt thermal insulation material of alumina-silica composition, having a substantial chromic oxide content, and of a density to be self-supporting, a diffuser in the plenum, and means to supply a gas/air mixture under pressure to force the same though the burner face member.
 2. A burner unit as claimed in claim 1, wherein the plenum is an elongated rectilinear body, the diffuser is V-shape in end elevation, and extends longitudinally of the body with the apex directed toward the burner face member, and the thickness of the burner face member is approximately one-fifth the total depth of the plenum.
 3. A burner unit as claimed in claim 2, wherein the face member includes approximately 4 percent chromic oxide.
 4. A burner unit as claimed in claim 1, wherein the face member includes approximately 55 percent silicon dioxide, 40 percent aluminum oxide and 4 percent chromic oxide with traces of sodium oxide and ferric oxide.
 5. A burner unit as claimed in claim 1, wherein the insulation material has a density of not more than 12 pounds per cubic foot, and a thermal stability of not less than 40 percent at 2,700* F.
 6. A burner unit as claimed in claim 4, wherein the material comprising the face member has a density of not more than 12 pounds per cubic foot, and can be fired for operation at an ambient temperature of approximately 2,000* F. 